Characterization of the molecular species formed by interaction of acetonitrile and copper(I) chloride in the liquid and solid phase

Summary The equilibrium vapour pressure of the solid complex, CuCl·MeCN, was measured at several temperatures. The enthalpy and entropy changes according to the following complex formation were determined: CuCl(s)+ MeCN(g)CuCl·MeCN(s); H=–56.9 kJ mol^–1 and S=–150 J mol^–1 K ^–1, respectively. Vapour pressure osmometry shows that a monomer-dimer equilibrium of CuCl exists in the acetonitrile solution. The equilibrium constant was found to be 0.93±0.08. A gas chromatographic technique was employed to determine the monomeric species as [Cu(MeCN)₄]Cl.     

Tandem intramolecular silylformylation and silicon-assisted cross-coupling reactions. synthesis of geometrically defined alpha,beta-unsaturated aldehydes

The palladium- and copper-catalyzed cross-coupling reactions of cyclic silyl ethers with aryl iodides are reported. Silyl ethers 3 were readily prepared by intramolecular silylformylation of homopropargyl silyl ethers 2 under a carbon monoxide atmosphere. The reaction of cyclic silyl ethers 3with various aryl iodides 7 in the presence of [(allyl)PdCl](2), CuI, a hydrosilane, and KF.2H(2)O in DMF at room temperature provided the alpha,beta-unsaturated aldehyde coupling products 8 in high yields. The need for copper in this process suggested that transmetalation from silicon to copper is an important step in the mechanism. Although siloxane 3 and the product 8 are not stable under basic conditions, KF.2H(2)O provided the appropriate balance of reactivity toward silicon and reduced basicity. The addition of a hydrosilane to [(allyl)PdCl](2) was needed to reduce the palladium(II) to the active palladium(0) form.     

Atropisomers of 1-(acyl or aroyl)-2-naphthylindolines. Isolation,X-ray crystal structure and conformational analysis

A series of pairs of stable diastereomeric atropisomers caused by restricted rotation around the Csp3-Csp2 bond of [2-(2-hydroxynaphthalen-1-yl)-3,3-dimethyl-2,3-dihydroindol-1-yl]-(3- or 4-substituted phenyl)-methanone or [2-(2-hydroxynaphthalen-1-yl)-3,3-dimethyl-2,3-dihydroindol-1-yl]-1-alkanone were isolated. The conformational analyses of the atropisomers were performed based on the X-ray crystallographic and (1)H-NMR spectral data. It became clear that rotation about the C2-naphthyl bond is restricted at room temperature, whereas the >NCO-Ar bond rotates freely.     

Electrooxidation of alcohols in an N-oxyl-immobilized rigid network polymer particles/water disperse system

The electrooxidation of alcohols in an aqueous disperse system with N-oxyl-immobilized poly(p-phenylene benzobisthiazole) network polymer particles (PBZT_NT-N-Oxyl) as a disperse phase was performed successfully in a simple beaker-type undivided cell under a constant current condition to afford the corresponding ketones, aldehydes, and/or carboxylic acid in moderate to good yields. Recycle use of both the PBZT_NT-N-Oxyl particles and the aqueous media could be achieved successfully by immobilization of additional N-oxyl moiety on the polymer particles in an appropriate interval. Notably, the shape and the particle size of PBZT_NT-N-Oxyl were not appreciably changed even after 60 times recycle use.     

HEMATOPORPHYRIN DERIVATIVE UPTAKE BY ATHEROMA IN ATHEROSCLEROTIC RABBITS: THE SPECTRA OF FLUORESCENCE FROM HEMATOPORPHYRIN DERIVATIVE DEMONSTRATED BY AN EXCIMER DYE LASER

Abstract A new diagnostic and therapeutic endoscopic system consisting of an excimer pulse dye laser is presented. This report demonstrates the accumulation of hematoporphyrin derivative (HpD) in atheroma as shown by the fluorescence of HpD using this equipment. Atheroma was induced in the aorta of WHHL (Watanabe heritable hyperlipidemic) rabbits, 5 mg kg⁻¹ HpD was injected intravenously and the rabbits were sacrificed 24 h later. The aorta was dissected and the localization of HpD was examined. Characteristic peaks of the fluorescence of HpD at 630, 665 and 690 nm wavelength were detected in the atheromatous lesion. However, in the fatty plaque, the emission peak at 630 nm was lower and the 665 nm peak faded away. No fluorescence with peaks was detected in the normal area. The ratio of fluorescence intensity in atheroma, border zones and normal areas was 10.4 : 5.0 : 1.0. On normal rabbits made atherosclerotic by diet and balloon damage, an ultra thin endoscopic catheter was inserted from the descending aorta of atherosclerotic rabbits under anesthesia. Essentially the same data was obtained by these studies in vivo as was obtained in the in vitro studies. The above data suggests the possibility of future applications of this equipment for diagnosis of atheroma.     

Detection of flexoelectric effect from 4-heptyloxy-4'-cyanobiphenyl monolayers at an air-water interface by Maxwell displacement current and optical second harmonic generation

The flexoelectric effect of 4-heptyloxy-4'-cyanobiphenyl (7OCB) monolayers at the air-water interface is studied by Maxwell displacement current (MDC) and optical second harmonic generation measurements. Though MDC was expected to increase during the compression of 7OCB monolayers in L2L2' phase from the MDC theory developed previously, decrease of MDC was detected in these phases. This abnormalous phenomenon is found to be due to the quench of flexoelectric effect by the flow orientation of monolayers.     

THE EFFECT OF CROSS-LINKING ON PHOTOCYCLING ACTIVITY OF BACTERIORHODOPSIN

Abstract— Purple membrane preparations from Halobacterium halobium were chemically modified with imidoesters. Dimethyl adipimidate (8.3 Å chain length) amidinates about five of the six free lysine residues whereas dimethyl suberimidate (11.3 Å) under the same conditions reacts with only 2–3 residues. Gel electrophoresis showed that the shorter chain length imidoesters were less effective than dimethyl suberimidate in oligomer formation. However, dimethyl adipimidate resulted in a more marked inhibition of the photoreaction activity. Monofunctional imidates, methyl acetimidate and methyl butyrimi-date, at comparable degrees of amidination, did not appreciably affect activity indicating that the presence of bulky groups on the exposed lysine residues does not cause the effects observed. Hence, the introduction of molecular mobility constraints by intramolecular cross-linking slows photocycling, and, therefore, inhibits proton pumping activity of bacteriorhodopsin. This indicates that conforma-tional changes of the protein moiety of bacteriorhodopsin occur during photocycling activity.     

Super-liquid-repellent surfaces prepared by colloidal silica nanoparticles covered with fluoroalkyl groups

A simple and easy method to prepare super-liquid-repellent surfaces is proposed. Sol-gel films were prepared by hydrolysis and condensation of alkoxysilane compounds. Both surface energy and roughness were controlled using colloidal silica particles and fluoroalkylsilane. When the fractional amounts of both colloidal silica and fluoroalkylsilane were optimized in the films, the film surface exhibited repellency to both water and oil. Finally, it was shown that the method proposed here would be applied to a simple one-pot coating for a uniform large area, and be useful for practical use.     

A concise synthesis of (3S,4S,5R)-1-(α-d-galactopyranosyl)-3-tetracosanoylamino-4,5-decanediol, a C-glycoside analogue of immunomodulating α-galactosylceramide OCH

A concise and convergent synthesis of the C-glycoside analogue 2b of immunomodulating α-galactosylceramide OCH 1b starting from readily available 2,3,4,6-tetra-O-benzyl-d-galactose 3 and l-arabinose 6 is described. The synthesis features the nucleophilic addition of an α-ethynyl sugar 5 to the phytosphingosine-precursor aldehyde 9 and would be applicable to a variety of C-glycoside analogues of interest.     

Optimization of ETV-ICP-MS conditions for the determination of multi-elements in semiconductor grade acids

The performance of an electro thermal vaporization (ETV) unit as a sample introduction device for an inductively coupled plasma mass spectrometer (quadrupole-ICP-MS) was evaluated. The technique was found to have several advantages over the conventional nebulization method. Some features of ETV-ICP-MS for single element determination have been investigated. Attempts were made to optimize the experimental parameters such as vaporization temperature, vaporization interval and carrier gas flow rate. The study highlights on the determination of Cr, Mn, Al and Na. A compromise condition for multi-element determination was suggested and tested from single-element optimum conditions obtained. 25 L solution was used for the analysis. Results obtained for the analysis of conc. HCl samples are also reported.